Ah, Roma! The pasta, the passegiata. But what we really visit Rome for again and again is its incredible history. The ancient Romans were innovators in so many different arenas, and perhaps the most impressive of their contributions are in architecture. From aqueducts to arches to domes to the perfect potion of concrete, even if the ancient Romans didn’t do it first, they often did it the best.

The Pantheon, one of Rome’s many UNESCO World Heritage Sites, is perhaps the pinnacle of their achievement. It is the original dome that inspired it all: the domes of St. Peter’s Basilica, the Duomo in Florence and the U.S. Capitol Building in Washington, just to name a few.

Michelangelo once said that the Pantheon was “built by angels, not by men.” But way before the Pantheon became the home of Christian angels, it was a pagan temple. How do we know? Its name translates to pan-theon: all the gods. Plus, there were a bunch of pagan statues decorating the place. So that one’s not a big mystery. But its mysteriously sturdy construction is.

There have been a few versions of the Pantheon; the first was done by Marcus Agrippa in 27 BC. You can still see his initials above the portico. The final one was built in 120 AD, under the rule of Hadrian. Believe it or not, that’s the same one still standing today. So, how in the world does a building stay standing for nearly 2,000 years, through earthquakes and invasions, not to mention millions of tromping tourists? That’s where that incredible ancient Roman engineering comes in.

The Pantheon’s dome is the largest the ancient world, 142 feet across. And it’s worth repeating: It’s still there. How? Think of a basketball inside a trashcan: that’s the basic structure of the Pantheon. The sides are helping to support the top. The Romans also created a special type of volcanic pumice, called pozzalana. It was not only stronger, but lighter than other types of concrete. They used their special concoction to make the walls of the dome thinner and thinner toward the top. And to cap it all off? The oculus, the 27-foot-wide hole in the roof. It serves as a keystone, to release some of the pressure, so the ceiling doesn’t cave in on itself.

The Pantheon also spawned many mysteries. We know that it was originally built as a temple to all the gods of pagan Rome. You can still see the niches where the statues of the gods stood. But, what were all those rows and rows of rectangular coffers above the statues for? And what does that oculus have to do with it? One theory says that when the light comes through the oculus and hits those coffers, it creates a sort of Roman Stonehenge or sundial, marking the days, months and years.

Another fun theory is that not only is the oculus the only light source for the Pantheon, the ancient Romans believed that the oculus would entice the gods to fly right on into their temple. Oh, and oculus means "eye," so the oculus is also the symbol of the gods’ eyes watching over us. So you’d better be good for goodness’ sake.

Here’s another theory: When you stand at the center of the Pantheon, and do a slow spin around, you’ll get the sensation that you’re at the center of the earth. That was intentional. This theory says that the Pantheon was meant to be a microcosm of the universe: all the gods surrounding you, the dome above symbolizing the heavens, and the oculus symbolizing the sun. Also, Emperor Hadrian was known to be a little astrology-crazy, so this theory of the Pantheon being a giant symbol of the cosmos is quite possible.

The final chapter in the Pantheon’s history is its modern-day transformation. Once Christianity became the religion of the land, old pagan temples were “recycled” into churches. And the Pantheon was no exception. All those pagan gods were moved out of their niches they’d lived in for hundreds of years, and replaced by saints. A cross was added to the pagan Egyptian obelisk in front of the entrance and the Pantheon was renamed Santa Maria ad Martyres when it was consecrated as a Christian church in 609. At the time, Romans believed there were ridding the Pantheon of its pagan demons by transforming it into a church.

From a pagan temple to a cosmic sundial to a Christian church, the Pantheon has lived up to its name of all things to all gods. And its architecture is pretty divine too.

Pan-theon means "all the gods," so the Pantheon was a temple to all the gods of ancient Rome. Statues of those pagan gods once decorated this interior. They were later replaced by Christian saints.
Curious Traveler